This invention relates in general to oxygen supply systems for providing oxygen for human inhalation, and more particularly, to such systems suited for use by aviators or parachutists who require a life support oxygen supply system while in oxygen short environments.
Various types of life supporting oxygen supply systems have been employed heretofore, particularly in association with military aviator and parachutist use. It has come to our attention that the prior systems have not been entirely satisfactory in assuring both the oxygen supply to the user and being compatible to the user's comfort at normal breathing pressures.
Constant volume oxygen flow systems have been provided heretofore which provide for a normal flow of oxygen to the inhalation mask, but without a suitable way to shut-off the oxygen flow, causing some oxygen to blow by the user escaping from the mask and frequently causing difficulty in exhalation by the user such that the user might have to separate the mask somewhat from his face in order to exhale. Where oxygen flow continues while the user attempts to exhale, the constant flow of the system buildsup excessive back pressure preventing the mask exhalation valve from opening properly and can result in improper mask operation, oxygen waste, user discomfort and respiratory fatigue.